The present invention relates to a bearing device for a vehicle axle characterized by an improved mounting structure for a rotation sensor.
As shown in FIGS. 7 and 8, a conventional bearing device for a vehicle axle has rolling elements 6 arrayed between an outer ring 2 and inner rings 5, through which passes an axle 3 and on which is mounted a pulser ring 4. A detecting member 7a of a rotation sensor 7 is inserted into an insertion hole 2a provided radially in the outer ring 2 so that the end of the detecting member 7a opposes the pulser ring 4, and a mounting member 9 of the rotation sensor 7 is secured to the outside surface of the outer ring 2 by bolts 8. The outer ring 2 is fitted in the fitting hole 1a in the bearing mounting member i.e. knuckle 1 on the chassis, and a mounting flange 2b of the outer ring 2 is fixed to a face 1b of the knuckle 1 by bolts (not shown in the figures).
By detecting a rotational velocity of the axle 3 by means of the rotation sensor 7 and the pulser ring 4, an antilock brake control system can be provided in the vehicle.
It is to be noted that there is a terminal box 7c fixed to the mounting member 9.
However, because the axle bearing device as thus described has a mounting flange 2b at approximately the middle in the axial direction on the outside surface of the outer ring 2 and the insertion hole 2a opens in the radial direction at approximately the middle in the axial direction on the outside surface of the outer ring 2, when the outer ring 2 mounting flange 2b is fixed to the end face 1b of the knuckle 1, the center line "c" of the insertion hole 2a is positioned near the end face 1b of the knuckle 1. As a result, the face 9a on the knuckle 1 side of the mounting member 9 of the rotation sensor 7 interferes by dimension "S" with the end face 1b of the knuckle 1, making it impossible in practice to secure the mounting member 9 of the rotation sensor 7 to the outer ring 2.
This problem can be resolved by, for example, shifting the face 1b of the knuckle 1 in the axial direction by an amount equal to dimension S to prevent this interference. However, there are cases in which the position of the face 1b cannot be shifted due to the construction of the knuckle 1.
Another way to avoid this interference is to make the mounting member 9 and the detecting member 7a smaller so there is no interference with the face 1b of the knuckle 1. However, this requires the diameter "d" of the detecting member 7a to be made extremely small, decreasing the detection performance of the rotation sensor.
Furthermore, another method is to offset the face 9a of the mounting member 9 by dimension "S" in the axial direction to the detecting member 7a in the direction away from the end face 1b of the knuckle 1 to prevent any interference. However with this method the overlap of the detecting member 7a and the mounting member 9 is width "W", becoming narrower, and the connection of the detecting member 7a and the mounting member 9 is thus weakened.